Skateboard

ABSTRACT

An in-line skateboard ( 10 ) includes a frame ( 18 ) located between-aligned wheels ( 14, 16 ). The frame ( 18 ) is pivotally connected at ( 32 ) to a leading wheel ( 14 ) by means of a fork member ( 30 ) which extends from an axle ( 15 ) of the wheel ( 14 ). The pivotal connection ( 32 ) is disposed below the level of the axle ( 15 ).

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a skateboard.

FIELD OF THE INVENTION

In conventional skateboards, a total of four wheels are arranged withone pair at the front and one at the back. All wheels are of very smalldiameter so as to fit under the deck with each pair possessing a singleaxle mounted on an oblique pivot, providing steering via the insidewheels moving in toward each other when the rider shifts weight ontothat side, and the outside wheels moving away from each other on theunweighted side of the board. Steering is thus provided by all fourwheels at once.

The pitfalls of conventional skateboard design are that the small wheelsare extremely sensitive to surface irregularities, making themimpractical and dangerous to use on anything other than very smoothsurfaces. Attempts have been made to overcome such problems by makingskateboards with larger wheels. However, larger wheels result in eithera higher deck (creating instability) or a much wider structure (with thelarger wheels extended out past the edge of the deck) which makes theboard too cumbersome and sluggish. The traditional skateboard layout hastherefore been restricted to relatively smooth surfaces since itsinception.

In an attempt to try and break away from traditional skateboardlimitations, new designs have been proposed. One such design was byBarachet, who proposed a two wheeled skateboard with both wheels alignedalong a central axis (in-line), like a scooter The design included aself-steering front wheel, fixed rear wheel and twopart deck, the firstpart for the front foot between the two wheels and the second part forthe rear foot behind the rear wheel.

Barachet's design included a front wheel held by a fork with a pivotpoint forward of the middle of the front wheel. By leaning to one sideof the board, a front pivot allows the front wheel to turn in theappropriate direction, steering the board. It has been found that whilethe front wheel does turn, these devices are extremely unstable and verydifficult to ride.

It has now been discovered that the reason for this instability is thatthe front wheel fork pivot point is higher than the axle of the wheel.This means the rider's weight is being applied above the mid point ofthe wheel, resulting in great instability and essentially making thedevice impractical and consequently, uncommercial. Further, it has beendiscovered that because the pivot point is above the front wheel axle,the arc that the wheel swings through when it turns is concave inrelationship to the ground. This has the very significant undesirableeffect of wanting to turn the wheel to the outside extremities when arider's weight is applied to the board.

A variation of Barachet's design is found in the German Grassboardsdeveloped by Kroher. Kroher has made only two changes to Barachet'sdesign, these being that the front wheel pivot point is horizontally inline with the axle and the single rear wheel is replaced by two wheelsside by side, a small distance apart. It is readily apparent that thedual rear wheels have replaced the single wheel to try and provide somestability to the board in an attempt to make it easier to ride. However,in requiring the lateral stability provided by the dual rear wheels, thesmooth transitional side to side turning characteristic theoreticallyoffered by an in-line two-wheeled board is lost.

The present invention seeks to alleviate some, if not all, of theaforementioned problems.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention there is providedan in line skateboard including a longitudinally extending framelocating aligned wheels, the wheels being mounted on axles, and one ofthe wheels being a forwardmost steering wheel, characterised in that theframe is pivotally connected to the forwardmost steering wheel at alocation below and in front of the axle of that wheel.

Preferably, a fork member is connected to the axle of the forwardmoststeering wheel, and an end of the frame is pivotally connected to thefork member at a location below the axle of the or each wheel.

More preferably, a leading end of the frame is pivotally connected to aleading end of the fork member at a location forward of and below theaxle of the forwardmost steering wheel.

It has been found that making the front fork pivot point lower than theforwardmost steering wheel axle (as well as in front of the axle)actually provides stability as a result of a convex arc created by theforwardmost steering wheel as it swings through its turning angle. Ithas been found that the application of a rider's weight thereforeautomatically centres and straightens the forwardmost steering wheel,creating stability and control.

Preferably, the pivot point is not made so low that it will hit theground in rough areas. It is generally kept as low as practicablewithout creating undue clearance problems. However, the further thepivot point is raised up from the ground, the less stable andcontrollable the skateboard of the present invention becomes. Therefore,there is a tradeoff between stability and ground clearance. It hasgenerally been found that the fork member may preferably be disposed atan angle in the range from 10-45 degrees, preferably to 20-25 degrees,from the horizontal. The fork member angle itself is an imaginary linedrawn from the wheel axle down to the ground via the exact centre of thepivot of the fork. The pivot arc angle is perpendicular to this and isan imaginary line drawn along the axis of the pivot.

It has also been found in the present invention that the use ofrelatively large wheel sizes such as of at least 300 mm in diameter,increases the stability of the system. In practice it has been foundthat the preferred wheel diameters are typically in the 400-600 mmrange.

The stability provided by the skateboard of the present invention issuch that wheel alignment springs or returns are not necessary to assistin riding. Even if the front wheel swings off centre when performingjumps and the like (when no rider weight is applied to the board), assoon as weight is reapplied, the front wheel is automaticallystraightened and stabilised. Further, it has been found that the forkmember, in conjunction with the wheel connected to it should be able toturn very freely.

It is therefore preferential to use one or more good quality sealedroller bearings in the pivot mechanism to ensure that the pivot isalways free to turn. Sealed deep groove bearings offer a good example ofa suitable type as they are designed to withstand high load from severaldirections as well as preventing dirt from entering.

It has also been found that rather than using a straight sided framewith a flat deck, it may be preferable to curve the frame out mosttowards the front (to allow for sufficient front wheel tuning), intowards the middle (which may be the lowest area closest to the ground)and out again slightly towards the rear to provide adequate width for arear foot position. Further, the widest points are typically the highestpoints to provide sufficient ground clearance during turns and thenarrowest points can be the closest to the ground. This type of complex3D curve also provides a structurally superior frame, as well as a moreaesthetically pleasing one.

As an alternative, it is possible to have a single frame tube extendingup from the pivot and around, directly over the adjacent wheel, and backdown to a reasonable ground height for the deck, extending rearwards towhere it may split into two sections to support the rear wheel.

As another accessory, a brake may be incorporated, mounted in typicalscooter fashion with brake pads and actuators acting on the rear wheel.However, it is envisaged that the rider could hold a brake lever in onehand, the brake lever being flexibly attached to brake pads via a cable.This way riders can still stand with a surfing/snowboarding style stancewhile being able to freely move their hand holding the brake leverbecause of the flexible cable. This has the added benefits of being ableto prevent the skateboard of the present invention from running awaywhen unattended, as well as allowing a rider to deliberately skid therear wheel under hard braking and go straight down steep hills withspeed control from light to moderate braking.

Two other alternatives are available for preventing a skateboard of thepresent invention from running away down a hill after stepping off. Thefirst is a wrist strap similar to that used by boogie-boarders in thesurf. This consists of a coiled length of elastomeric cord with “Velcro”attachments at each end (one for the wrist and the other for the frameof the skateboard).

The other alternative is a more purpose built rear foot activated brake.In this instance, there may be provided a spring biased button rising upthrough the deck where the rear foot is positioned. Under the springbiased button there may be a plate with a bottom section attached to thebutton and an upper section touching the rear wheel. Without rear footpressure being applied to the button (when not being ridden) the uppersection may maintain pressure on the rear wheel. As soon as a rider'srear foot is positioned on the rear of the deck (and over the button)the upper section of the plate releases its pressure from the wheel.This means the rear wheel is free to turn as soon as a riders rear footis in position on the board but as soon as the rider steps off, thebrake is automatically applied and the skateboard stops.

This brake design also may be used as a progressive brake while ridingsimply by angling the rear foot slightly to allow the button to rise upslightly under the foot to apply the required degree of braking power.

A further accessory which may be used is a form of foot strap to providea more snug fit for the feet while riding a skateboard according to thepresent invention. The foot strap may be formed of angled, flexibleplates that extend up from the frame and back for the front foot andforward for the rear foot. Riders simply turn their feet around slightlyto slide under the foot straps and rotate their feet back to release.This system is designed for ease of use without the difficulty of tryingto slide in and out of conventional foot straps and the resultingdangers created by slow release.

However, advanced riders could prefer to use conventional foot-straps ofthe type used by sailboards for extra foot security when performingmanoeuvres such as jumps.

Also, the skateboard of the present invention could be provided with adetachable set of handlebars. For example, by incorporating aquick-detach fitting at the front wheel axle or adjacent the fork memberpivot point, scooter type handlebars may be fitted onto the skateboard.With handlebars attached, the skateboard acts as a scooter so that arider can scoot along to a venue, then detach the handlebars and ridethe skateboard down hills before re-attaching the handlebars to returnhome. The skateboard of the present invention may also be used inconjunction with kites.

By holding onto a handle attached to an end of a kite string askateboard may become mobile via the power of the wind, enabling gybingand tacking type manoeuvres to be achieved.

Further, the skateboard of the present invention is well suited to beingpowered by motors via the non-steering wheel, Small petrol and electricmotors can be used to drive the skateboard forward on flat surfaces oreven power it back up hills after rolling down without power. Electricmotors are convenient for this as the motor can be recharged on the rundown the hill and then switched on to drive the board back up the hillto minimize overall battery drain.

It is envisaged that the skateboard of the present invention may operateon surface conditions ranging from smooth asphalt/bitumen to grass anddirt such as local parks, car parks and open sloping fields.

Just as the front wheel of the skateboard of the present invention maybe selfsteering, in another aspect of the present invention, the rearwheel may also pivot in similar manner to the front wheel should atighter turning radius be required. Also, it is envisaged that the frontwheel could be fixed with the rear wheel pivoting as anotheralternative.

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of a skateboard in accordance with thepresent invention;

FIG. 2 is a plan view of the skateboard of FIG. 1;

FIG. 3 is a side elevation of a front wheel of the skateboard of FIG. 1in enlarged scale;

FIG. 4 is a plan view of the front wheel of FIG. 3;

FIG. 5 is a perspective view of the skateboard of FIGS. 1 to 4 showingthe convex arc of the front wheel as it sweeps through its turningrange;

FIG. 6 is a side elevation of a rear wheel of the skateboard of FIG. 1to an enlarged scale showing a brake in an operational condition;

FIG. 7 is a view similar to FIG. 6 showing the brake in anon-operational condition;

FIG. 8 is a plan view of the rear wheel of FIG. 7;

FIG. 9 is a side elevation of an embodiment of a fork pivot which may beused in the skateboard of the present invention.

FIG. 10 is a plan view of the fork pivot of FIG. 9.

DESCRIPTION OF THE INVENTION

In FIGS. 1 to 4 of the accompanying drawings, there is shown askateboard 10 in accordance with the present invention including a frame12, a leading wheel 14 and a trailing wheel 16. The wheel 14 is mountedfor axial rotation on an axle 15 whilst the wheel 16 is mounted foraxial rotation on an axle 17. Further, as will be described the leadingwheel 14 is arranged for lateral pivotal movement whilst the trailingwheel 16 is laterally fixed.

The frame 12 includes a pair of spaced longitudinally extending framemembers 18 extending from front to back of the skateboard 10. Each framemember 18 includes an outwardly curved leading portion adjacent thewheel 14 as seen in FIG. 2, a mid-portion in which the frame members 18curve inwardly so as to be relatively close together, and a rear portionadjacent the wheel 16 in which the frame members are curved outwardly.As seen in FIG. 1, the frame members 18 curve longitudinally upwardly toa point adjacent the mid point of the wheel 14 and then curve downwardlytowards the middle of the frame 12 and then curve upwardly to the axle17 of the wheel 1.6. The widened portion adjacent the front wheel 14enables the wheel 14 to pivot through a substantial angle. The widenedposition adjacent the rear wheel 16 enables the rear portion of a deck20 to be wide enough to accommodate a foot comfortably. It can also beseen that the wider frame portions have relatively high ground clearancecompared to the mid region of the frame.

A two part deck 20 is mounted across the frame members 18. The leadingpart of the deck 20 is a flat member having a front “L”-shaped toe-jamfoot support 22 mounted thereon. The rear part of the deck 20 is in theform of a flat plate having a rear upwardly extending foot stop 24.

The wheel 14 is provided with a tyre 26 whilst the wheel 16 is providedwith a tyre 28.

As can be seen in FIG. 1 the frame members 18 extend forwardly beyondthe axle 15 and are disposed below the level of the axle 15 adjacent thewheel 14. As shown the frame members 18 are connected to the wheel 14 bymeans of a fork member 30 which extends around the front of the wheel 14and extends rearwardly to the axle 15. The fork member 30 is fixedlyconnected to the axle 15 and is also pivotally connected by means of apivot at 32 to the frame members 18 at their leading ends. The pivotalconnection point is, as can be seen in FIG. 1, below the level of theaxle 15 and also below the level of the axle 17.

As can be seen in FIG. 3, a line 34 from the axle 15 through themidpoint of the pivot 32 subtends an angle 36 with the ground. The angle36 is the fork member angle discussed hereinabove. Further, a line 38passes through the pivot 32 at right angles with the line 34 andsubtends an angle 40 with the ground. The angle 40 is the pivot arcangle discussed hereinabove.

Referring to FIG. 4 the fork 30 and the wheel 14, including the tyre 26,are free to swing backwards and forwards via the pivot 32, between theframe members 18. The swingarm fork assembly 30 has appropriately shapedside plates 100 which act as stops against the frame members 18 toprevent the wheel 14 from swinging too far and contacting the tyre 26against the frame members 18.

In FIG. 5 there is shown the front wheel 14 and the convex curve 42through which the front wheel 14 moves.

If the centre of the pivot 32 were at axle height with the pivot arcangle 40 at 90 degrees to the ground (vertical) then the wheel itselfwould effectively sweep around, horizontally, drawing an imaginary large3D donut.

Now, if the centre of the pivot 32 is below axle height as in thepresent invention with the pivot arc angle 40 at say 45 degrees to theground then the wheel itself effectively sweeps around, drawing animaginary large 3D donut on a 45 degree tilt in this example. Thehighest point of the donut is found midway between the frame members 18.Consequently, if weight is applied down onto the pivot 32 (i.e. riderstands on board) then the swingarm fork 30 immediately centres itself tothe highest point of the donut (the top of the convex curve 42).

In FIGS. 6 to 8, there can be seen more clearly one embodiment of abrake mechanism 50 for the skateboard 10 of the present invention.

As can be seen in FIG. 6, the brake mechanism 50 comprises an “L”-shapedmember 52 which is normally spring biased by means of a spring 62 sothat an upwardly extending braking member 54 bears against the peripheryof the tyre 28 of the rear wheel 16. Further, the member 52 has agenerally horizontal lower member 56 disposed below the rear part of thedeck 20. The lower member 56 has an upwardly extending leading portion58 which projects through an aperture in the deck 20 and is connected toa generally horizontal button portion 60. When a rider has a foot on therear portion of the deck 20 the foot depresses the button portion 60which pivots the portion 56 and the member 58 downwardly. This causesthe braking member 54 to disengage from the periphery of the tyre 28 ofthe wheel 16 as shown in FIGS. 7 and 8.

When the rider removes his foot from the rear portion of the deck 20 the“L”-shaped member 52 reverts to the position shown in FIG. 6 and brakingforce is therefore applied to the wheel 16.

In FIGS. 9 and 10 there is shown a mounting arrangement for the swingarm fork member 30 to the pivot 32. As can be seen in FIG. 9, the forkmember 30 may include a top plate 80 and a parallel base plate 82.

As can be seen in FIG. 10, the plates 80 and 82 extend through an arc 84in front of the wheel 14.

The plates 80 and 82 are both fixedly connected via side plates 100 andthe fork assembly interconnected by a bolt 86 which passes throughaligned apertures in the plates 80 and 82 and is threadedly engaged witha nut 88 to retain it in place. Surrounding the bolt 86 between theplates 80 and 82 is a bearing housing 90 fixedly connected to the frontof each frame member 18 and containing an upper roller bearing 92 and alower roller bearing 94. A flanged connection bush 96 fits into thebearing 92, whilst a flanged connection bush 98 fits into the bearing94. The bushes 96 and 98 are contiguous with the bolt 86 and the plates80 and 82.

With the arrangement shown in FIGS. 9 and 10, the bolt 86, the plates 80and 82 and the bushes 96 and 98 are able to rotate axially relative tothe bearing housing 90 and the frame since they are free to rotate bymeans of the roller bearings 92 and 94. In use, the board 10 is riddenby a rider placing his or her feet on the deck 20, the front wheel andthe back foot on the deck nearest the rear wheel, probably against therear foot support 24. Further, the button 60 is depressed by the rearfoot to disengage the brake mechanism 50.

The skateboard 10 can then be ridden, particularly downhill, on a widevariety of surfaces including smooth tarmac or concrete but also overuneven ground such as grassed surfaces.

The arrangement of the fork member 30 being connected to the frame 18below the level of the axle 15 ensures that the leading wheel 14self-centers whilst the skateboard 10 is being ridden in an uprightmanner and only cants to one side or the other when the rider induces alean in the skateboard 10 to cause it to travel along a curved path.Thus, the direction of travel of the skateboard 10 is controlledautomatically by rider weight shift without the need for separatesteering mechanism or devices such as handlebars to control pivotalmovement of the leading wheel 14. Modification and variations such aswould be apparent to a skilled addressee are deemed within the scope ofthe present invention. For example, whilst the two wheeled skateboardembodiment is preferred it is envisaged that the skateboard could havemore than two wheels. For example, instead of a single wheel at therear, there can be pair of wheels mounted on a single axle or axis.

What is claimed is:
 1. An in line skateboard including a longitudinallyextending frame locating aligned wheels, the wheels being mounted onaxles, and one of the wheels being a forward-most steering wheel,wherein the frame is pivotally connected to the forward-most steeringwheel by a pivot located entirely below and in front of the axle of theforward-most steering wheel, the pivot being disposed relative to aground surface at a leading acute angle which subtends between theinclination of the pivot and the ground surface, such that when a rideris mounted on the skateboard the weight of the rider stabilizes theforward most steering wheel of the skateboard.
 2. An inline skateboardaccording to claim 1 comprising two wheels mounted on respective axles.3. A skateboard according to claim 2 where one of said two wheels trailsthe other of said two wheels wherein said trailing wheel isnon-pivotally connected to the frame.
 4. A skateboard according to claim3 wherein the frame includes two longitudinal members which arerelatively widely spaced adjacent the forward-most steering wheel topermit transverse pivotal movement of the forward-most steering wheel.5. A skateboard according to claim 4 wherein a deck is supported by thelongitudinal members to provide a mounting for the feet of a rider.
 6. Askateboard according to claim 3 wherein the forwardmost steering wheelis connected to the frame by a fork member.
 7. A skateboard according toclaim 6 wherein the frame includes two longitudinal members which arerelatively widely spaced adjacent the forward-most steering wheel topermit transverse pivotal movement of the forward-most steering wheel.8. A skateboard according to claim 6 wherein the fork member is disposedat an angle in the range from 10 to 45 degrees from the horizontal.
 9. Askateboard according to claim 8 wherein the frame includes twolongitudinal members which are relatively widely spaced adjacent theforward-most steering wheel to permit transverse pivotal movement of theforward-most steering wheel.
 10. A skateboard according to claim 8wherein the fork member is dispensed at an angle in the range from 20 to25 degrees from the horizontal.
 11. A skateboard according to claim 10wherein the frame includes two longitudinal members which are relativelywidely spaced adjacent the forward-most steering wheel to permittransverse pivotal movement of the forward-most steering wheel.
 12. Askateboard according to claim 6 wherein the fork member is fixedlyconnected to the axle of the forward-most steering wheel and extendsforwardly to a pivotal connection with the frame.
 13. A skateboardaccording to claim 12 wherein the fork member is disposed at an angle inthe range from 10 to 45 degrees from the horizontal.
 14. A skateboardaccording to claim 12 wherein the frame includes two longitudinalmembers which are relatively widely spaced adjacent the forward-moststeering wheel to permit transverse pivotal movement of the forward-moststeering wheel.
 15. A skateboard according to claim 12 wherein the forkmember is connected to the axle on opposite sides of the forward-moststeering wheel and extends forwardly on both sides of the forward-moststeering wheel and has a bridging portion extending around a frontportion of the forward-most steering wheel, the bridging portioncontaining the pivotal connection to the frame.
 16. A skateboardaccording to claim 15 wherein the fork member is disposed at an angle inthe range from 10 to 45 degrees from the horizontal.
 17. A skateboardaccording to claim 15 wherein the frame includes two longitudinalmembers which are relatively widely spaced adjacent the forward-moststeering wheel to permit transverse pivotal movement of the forward-moststeering wheel.
 18. A skateboard according to claim 1 wherein means forbraking are provide to prevent rotation of one or more of the wheelswhen a rider steps off or falls from the skateboard.
 19. A skateboardaccording to claim 18 wherein the means for braking include a memberarranged to bear against a wheel when a rider is not on the skateboard,but to be moved away from the wheel under pressure from a riders footwhen a rider is on the skateboard.
 20. A skateboard according to claim 1wherein each wheel has a diameter of at least 300 mm.
 21. A skateboardaccording to claim 20 wherein each wheel has a diameter in the rangefrom 400 to 600 mm.